Expansion valve



Oct. 13, 1942. A. B. NEWTON EXPANSION VALVE Filed sept. 26, 1958 Jill :Summer Alwin BoNwton Lttorneg Patented Oct# 13, `1942 b b 2,2s`ni,`of1i` l s rxrANsioN vALvE l y e Alwin B. Newton,lMi`nneapolis`,Minn., assignor to Minneapolis-Honeywell Regulator Company,` Minneapolis, Minn., a corporation ci' Delaware Application september 26,1938,sena1N0.2s1,ss4

n a substantially constant degree offsuperheat for ,l varying lpressures at the evaporator outlet.

, y s e 17 claims; This invention relates to expansion 'valves for use in refrigeration systems and more particularly trolled by `superheat at the evaporator outlet; l

" This application isa continuation `in part of 1 my co-pending application, E Serial `No. 192,818,

medrrebruary 26, 1938.` s l Thermostatic expansion Jvalves may be divided `into two general classiiications,namely,` those "whose operating elements arein the forni` of b, bellows and those `employing,diaphragrrls `as` the operating elements.v In the bellows type of expansion `valve, `diiiiculty has been experiencedwin refrigerant l` onone side and `to `humidatrnospheres on the other side, thus causing rapid deb l terioration of the bellows,` whereas if the `bellows are` maintained entirely b out of `contact with the yatmosphere, the main cause of deterioration of the bellows is removed.` This I have been able to lows,thereby `retaining theknown advantages of the bellows type of thermostaticy expansion valve provision of` a thermostatic b expansion valveof ducing the danger `of rupture ofthe bellows;

Anotherobject of my invention is the arrangeto expansion valvesof the automatic type con-` ,While eliminating `the disadvantage thereof. `Oney of the" objectsfof my invention is `therefore the 30 ment `of thebellows so that in case any one of A further objectbol` the invention isthe provision of an expansion valve which maybe interchangeably used with refrigeration systemsusing diilerent kinds of refrigerants. l

Another object's the provision of means for I connecting the valve operating means to the .in-

the past due to the fact l,the 'bellows is exposed toy i 'tem in which an expansion valve embodying a partly in `cross section;` b n e b Figure 2 isla section taken along the line 2-p-2 accomplish fby a` novelarrangement of the beli terior of theevaporator outlet at a single point. Other objects will become apparent` upon a study ofthe specification, claims, and appended drawing,` iin,` which `like reference characters represent like parts in the various views and in which: b b l Figure 1 isa view showing a refrigeration `sys- `lslreferred form of my invention is illustrated of Figure 1; and

Figure 3 is a `view along the line v3--3 of Figure 1Q Referring more particularlyto the drawing,` a conventional form of refrigeration system isillusjtrated, this :system including a compressor Ill for compressing a. refrigerant and forcing it through pipe II toa condenser I2 wherein the refrigerant -ishcondensedandflows to a receiver I3 from the bellowsrshould rupture,- no refrigerant would be lost therethrough. s l

lAfurther `object ofiny invention is theprovision of means `to eliminate-hunting ofthe'valve. l

1 which it flows through a pipe I4 through expansion valve I5 where thefrefrigerant is expanded, the` expanded refrigerant thus flowing through pipe,l6 to an evaporator II wherel the refrigerant 1 absorbs heat from thesurrounding atmosphere and evaporates and-then iiows through pipe I8 Vbaclizftofthe compressor I0. The compressor I b `Another,"object is the provision of a power unit, "f

` the danger off leakage ofthe refrigerant, together with means for compensating `fcrthe spring rate ofthe bellows. f l y "i f e ,f

A further object of my "invention'is the novel arrangement ofy athermostatlc `expansion valve i evavoretef Y `bulb is employed.

l sion yof a novel `bellows:arrangement for operating a thermost "operated 1in accordance with thesuperheat at the;

A furtherxobject ofthe invention is the pievi;

for `an,` expansion valve which f may` readily be maybe controlled in any conventional manner.`

f i The expansion `valve `I includes a valve casing 2n anda chamber 2 I, housing the operating mechanism. Valve casing'ZU includes an inlet 22 to which is suitably connected fin any suitable mannerthe pipe I4, and-an outlet 24 to `which is suitably connected the pipe `I B. `Refrigerant flows f throughitheuinlet 22 through "a b passageway 23 ating bellows for the valvelr further reducing t into a chamber 2,5; A valve element 2 Ecooperating "with a `reniovable valve seat 21 c ontrols the flowlof .refrigerant from-the chamber 25 intoia r passageway 20 which leads tothe outlet 24. The

valve element is carried byla lever pivoted at 3l in a recess formed in the outer wall of the :valve casing 20; A spring32 bears against the 50A outlet fwherein no `sealed operating b downwardly extending -arm 33 of the lever 3l), this sprlngbeingseated ina suitable recess formed in x the l*outeiywall of the valve chamber 20. Valve tic expansion valve `so as t6 maintain 55 n casing'jland the casing 2| may be connected together finany suitable manner and flanges 34 and 35 maygbe proved on ythe outer .walls of the chambers from one another.

casings 20 and 2| and suitably secured together by bolts 36. Pins 31 may be provided for properly aligning the two casings together and a sealing gasket 38 of any suitable material may be interposed between the casing's. Casing 20 may be open on that portion which is contiguous the casing 2 I, there being a suitable opening 39 formed in the wall of the casing 2| which separates the two Lever 30 may be in the form of a yoke as illustrated in dotted lines in Figure 3 and includes arms 40 which extend through the opening 39 into the casing 2|, these arms 40 being biased upwardly by means of spring 32 into engagement with pins 4|. These pins 4| are carried and moved by the operating mechanism in casing 2| as will be clearly described later.

The casing 2| houses a pair of bellows 45 and 46 which are axially aligned and are connected together and separated from one another by a cup-shaped member 41. The bellows 45 may be secured between a member 49 and the upp4 wall of the casing 2|, member 49 being secured 'i the upper wall of the casing 2| in any suitable Inanner. A cup-shaped member 48 is provided in the lower wall of the casing 2| and the bellows 46 may be secured between this member and the lower wall portion of the casing 2 The member 41 forms a wall which separates the bellows 45 and 46 into a pair of separated chambers and in the upper portion of the member 41 is suitably fitted a nipple, 50 having a restricted opening therethrough and providing communication between the interior of the bellows 45 and the chamber formed between the outside of the bellows 45 and 46 and the casing 2|. It will be noted that this chamber formed between the bellows and the casing 2| is in communication by means of the opening 39 in the interior wall of casing 2| with the valve chamber 25 so that the valve chamber 25 and the chamber surrounding the bellows 45 and 46 are at all times during the operation of the system lled with Warm refrigerant 'entering valve chamber 25 through inlet 22.

Connected to the bottom portion of member 41 is a vertically extending rod 52 which extends through an opening in the bottom portion of member 49, a bellows 56 being suitably secured to this rod at a point remote from the bottom thereof andthe lower portion of this bellows being suitably secured to the lower Wall portion of member 49. To the upper portion of rod 52 is threadedly secured'a nut 58 against the under side of which bears a compression spring 59. The lower portion of spring 59 bears against the lower portion of a yoke 60, as more clearly illustrated in Figure 2, the upper portion of this yoke being connected to a rack 6| with which engages a gear 62 connected to a motor 63 for a purpose to be later described. At any given time the yoke 6D will be held in a xed position and the spring 59 bearing against the bottom of the yoke and the nut 58 biases the rod 52 and accordingly the member 41 connected thereto in an upwardly direction. l

Secured to the cup-shaped member 4R in the bottom of casing 2| is a fitting 65 having an inlei', 66 communicating with a passageway 61 which communicates with the interior of the bellows 46. A pipe 68 is suitably secured within the inlet 66 of tting 65, the other end of this pipe being secured by a suitable tting 69 to the outlet of the evaporatorv |1. This fitting 69 may include a nipple threaded at one end into the outlet of the evaporator and a nut 1| threaded onto the other end of the nipple and securing the end of pipe 68, which may be ared, between the nut and outer portion of the nipple. Extending through the pipe 68 and spaced from the walls thereof is a small tube 14 which is suitably secured to the fitting 65 and communicates with a passageway. 15 extending upwardly through the fitting 65. To the outlet portion of passageway 15 is secured a small tube 16 which may be spirally arranged within the bellows 46 and of flexible material. The upper end of this tube extends through a wall of the wall member 41 separating the bellows 45 and 46 from one another. Pipe 14 extends through the nipple 10 and into the outlet of the evaporator I1, this pipe terminating in a nozzle 18, which nozzle is directed away from the evaporator |1.

The bellows 46 is in communication by means `of the pipe 68 with the outlet of the evaporator |1 and is accordingly subject to variations in the pressure of the refrigerant at the outlet of the evaporator. The upper bellows 45 is in communication by means of nipple 50 with the cham ber formed between the bellows 45 and 46 and the casing 2| so that; the warm refrigerant surrounding these bellows is able to pass through the small passageway in the nipple 50 Where it is eX- panded into the bellows 45. This bellows is also in communication by means of the tube 16, the tube 14 and nozzle 18 with the outlet of the evaporator so that the pressure existing within the bellows 45 may be lconsiderably less than the pressure of the refrigerant surrounding the bel.- lows, this latter refrigerant being on the high pressure side of the refrigeration system. There will accordingly be a considerable pressure differential between the exterior and the interior of bellows 45. It is well known that a gas passing through a small nozzle has a critical pressure. In other words, when the pressure differential through the nozzle has reached a certain value, the nozzle will pass a maximum amount of gas which amount will not be increased as the pressure drops. With common refrigerants the critical pressure value will be somewhere in the neighborhood of .9'7 as the liquid refrigerant expandsy into a gas. In other words, if the pressure on the low pressure side of the nozzle is less than 97% of the pressure on the high pressure side of the nozzle the same amount of refrigerant will pass therethrough, for a given head pressure, as will pass if the pressure on the low pressure side of the nozzle is further decreased. Therefore the amount of refrigerant owing through the nipple 50 will not vary appreciably during the operation of the system since the pressure Within the bellows 45 will always be less than 97% of the pressure on the outside of the bellows so that there will be a constant ow from the chamber surrounding the bellows 45 and 46 of the refrigerant through the nipple 5D and into the interior of bellows 45.

The refrigerant, upon passing through the nlpple 50 expands and enters the chamber 45 and becomes evaporatedthus filling the chamber 45, tube 16, and tube 14 with evaporated refrigerant. It should be noted at this point that the bellows 45 is surrounded by warm liquid refrigerant from the condenser I3 so that the refrigerantr within the bellows will remain in the evaporated condition. The refrigerant passes outwardly through pipe 14 to the nozzle 18. This nozzle is also of small size so that the refrigerant will leave the pipe 14 through this nozzle at a slow rate. Because of the flow characteristics of the nozzle i greater `weight-` of refrigerant will flowftherethrough per unit time than whenthe refrigerant is in gaseous `form so that the amount of refrigf-el'ant in bellows 45 will dependupon the state t of the refrigerant at the nozzle "Il,` which in turn depends `upon the l temperature at the evaporator outlet. "The refrigerant at the `enol` of the pipe 14 and the no-zzlefl is subjected to I,the temperdense` the` refrigerant in" the nozzle 'I8 so that therefrigerant "willow through the nozzle `'lll at a greater `weight` rate thanfif` the refrigerant l were in""gaseous `form. ""The nozzle 18` and the end of thepipe 14 accordlnglyiformla condensiPgsurface. The orice of the nozzle 'I8 will act trance thereof,` andthe temperature of this liouidrefrigerant determinesthe 4pressure inthe tor. The `pressureacting" downwardly against s the plate member" 4lwill aceordingly depend upon theutemperature of `therefrigerant at the ature of thefrefrigerant"leavlngthe evaporator "I'l and since thslternperature is low, itwill con" l `loellows 45, aoolpocordingly thispellows responds` greater` rate. For this` reason, the amount `of superheat in the return line where thereilective areasof the bellows are equal,l varies with vary- .s ing temperatures therein, the lower the ternperag` ture `the greater amount `of superheat since `the degree of superheat depends upon thedifference t tive area of the power bellows somewhat smaller to maintain a smallfliquid surface at the ento the pressure `corresponding to the temperature l of the refrigerant in theT outlet oftheelrapora-` l evaporatoroutletand since the bellowsS is subl seen that the plate 41 movesjin 5, in accordance with variations in` superheat of t i thereirigerant in the `evaporatoroutletl r r p The movement otpins 4|` downwardly causes the opening of valve 26,"this downward "move- "fluent of the `pins occurring when the pressure sure is the pressure corresponding to Vtheterni perature of the refrigerant r r 1. suction pressure atthe levaporator outlet plus l(the pressure exerted `by spring`w5`9 or in other "words, when "thesuperheatat the outlet rofthe evaporator reaches a predetermined value.` The ""opening of the valve 26 permitsan` increasedflow fof refrigerantthrough piper I'6 andevaporator "I 1 whereupon the pressure at the evaporator outlet increases and/or the ltemperature decreases and the valve is again permitted `to move towards olosed position. s f s 'Irhe provision of belloilvsl` which forms a sealingbellowsfbetweenthe rc`d.152 andwtheupper yportion of` `bellows of the bellows 45 sincethe pressure within this "llbellows exerts an `upward force on the bellows acting downwardly on the plate 41,which pres-` is` greater than the reduces the effective area l Vit is assured zle located vating nll is required,

`evaporator outlet by I8l eliminates thenecessity of using the customary temperature bulb having a sealed ll while producing the same results asfhas heretofore been obtained` with the sealed ll. Itis also pos-` sible tornake` `a single" Connection to the suction line lforthe' power bellows and the pressure bellows even `where the outlet lineis of small size which might not be possiblefwiththe conventional construction utilizirig `the bulb with` the sealed ll. By reason of this single` connection that the bellows `will accurately correspond to the"superheatat a single point in the outlet of the evaporator and by having the nozithin the suction line it is possible o' obtain quicker response of the valve to variations in sperheat. AlsoQsince Vnosealed operthe expansion valve may be interchangeably kused with refrigeration systems using different Toprevent hunting of the valve, I have provided a suitable friction `damping means foppreventingthe operation of the valve in response to minute changes in superheatat the evaporator outlet.` A friction plate 80is xeldly secured` to the upper wall of the casingZl,` this platebearing against one side of the rod 52.` A second plate `8| or any suitable friction *material "is slidably i supported `on` the top of t theVcasing 2| diametri-` place by means `1 l56 tending toniovethe rod 52 upwardlyso thatf the eiective areaof` lof bellows 46 by an amount corresponding to the areaof the bellows 56. `By"reason` of this,` when spring 5.9"` is properly adjusted it lis possible to `maintain a `constant superheat at the evaporator outlet so that a" uniform portion ofr evaporagardless of" the `temperature and `pressure existingl lat theoutlet thereoflf" This `would not be rue were thefeilective area Tof thetwo `bellows temperature for known `refrigerante `isnot `a "straight line relationship so` that `the pressure exerted by the bellows45 which `will be termed corresponding tor I1 will beavailable for cooling purposes rebellows 4-5 is less than that equal since "the relation between" lpressure and bears against the s whereby the vdanger cally opposite from the plate `lili, thisplate being slotted 'as at 82 and being slidably` held `in of a bolt 83. `A spring BtA is, to the side of casing 21 'and end of the platell. The force exerted by this `spring on the, plate 8| may be Varied `by means of a bolt 8,6 threaded intosthe side of the casing 2| Thus a force resisting the movement of the `rod 52 and therefore of the valve 26 is provided bytle plate 8 I, this force secured Aas at B5 rbeing adjustable by means ofthe bolt 86 so that it will require more than just a minute change in the degree of superheat at the evaporator outlet yto `cause any movement of the valve 26,

of the valve hunting in respouse to minute changes in superheat may be effectively prevented. p

The sealing bellows 56, as wellas the bellows 45 and 46` and the tube that may be suitablycompensated fori" This compensatingvmeans may include a circular spring 90 suitablylsecured as at 9| to the upper` portion of the member 49,`this spring having a single turn with the ends thereof spaced apart as illustrated. Suitable toggle links 93 and 94 are "notched at their outer `ends and t over thereduced inner portion of spring 90, the inner ends `of these links being reduced and tting within notches 95 formed in the upperportion ofrod 52. fUpon a downward valve openingmovelnent of the plate member 41, theibellows 46 and 56 andtube 18 kinds of refrigerante withi" Vout affecting the superheat `rxl'aintainedat the properly adjusting the valve. Y

1E will have a spring rate tend to become compressed and this compression of the bellows and tube will tend to oppose the .downward movement of the plate 41. Similarly,

the expansion of bellows 45 tends to cause the downward movement of plate 41. member 52 moves downwardly, the inner portions of toggle links 93 and 94 will also be moved downwardly and by reason of the force exerted by spring 90 these links will exert a downward force on the rod 52 which force increases as the plate 41moves downwardly and the bellows and tube become more compressed. This action of the toggle links in tending to urge the rod 52 downwardly may be arranged to just compensate for the spring rate of the various parts so that these parts will have no effect Whatever on the movement of the plate v41 and therefore will not tend to oppose the opening of the expansion valve.

Any suitable condition responsive device such as a thermostat may be mounted in the space beingcooled, this thermostat comprising a bimetallic element |.0I and an arm |02 connected to the bimetallic element |0| yand movable thereby in response to changes in temperaturein the space being cooled. Arm |02 is arranged to sweep across a resistance |03 in response to temperature changes in the space being cooled, this resistance being connected at 'its ends by means of conductors |04 and |05 toterminals |06 and |01 of the motor 63. The bimetallic Aelement |0| is connected by means of conductor |08 to motor terminal |09. Power may be Jsupplied to the motor by means of conductors; 0 and connected to a suitable source of power, notr shown. Motor 63 is of the proportioning type and may be constructed in the manner shown by the patent to D. G. Taylor No. 2,028,110 issued January 14, 1936. This motor is a reversible motor, the direcv tion of rotation and the extent of rotation being dependent upon the position of arm |02 with respect to resistance |03 as is clearly set forth in that patent;` As the temperature in the space being cooled rises, the arm |02 moves to the right across the resistance |03 and causes rotation of motor 63 an amount proportional to the extent of movement of the arm |02 ina direction to cause a decrease in the tension of spring 59 so that the amount of superheat required to open the valve 26 is decreased. In other words, the pressure corresponding to the temperature of the refrigerant at the evaporator outlet which is required to overcome the force exerted by the suction\ pressure within the bellows 46 and the spring 59 is decreased due to the decrease in the force exerted by the spring 59, and by decreasing the amount of superheat at the evaporator outlet, a greater portion thereof is available for cooling purposes, Conversely if the temperature in the space should drop indicating the need for less cooling within the evaporator, armv |02 of thermostat |00 moves to the left over resistance |03, causing the motor to rotate in a direction to increase the force of the spring-59 so that a greater amount of superheat is required to open the valve and a. smaller portion of the evaporator will be filled with liquid 'refrigerant and` accordingly will be available for cooling purposes. The downward movement of'the' yoke member 60 may be limited by means of the friction vclamping means consisting of the members 80 and 8|.

It will be noted that with the bellows 40 arranged in the manner illustrated, that both sides thereof are at all times exposed to refrigerant and at no time is any portion of the bellows exposed to the atmosphere so that the life of the bellows is materially increased and the main cause of rupture thereof is eliminated. The superheat that will be maintained at the evaporator outlet for any given temperature in the space being cooled may be varied by adjusting the positionof nut 58 on the rod 52 so as to vary the tension of the spring 59 and accordi ingly vary the force required to open the valve for any given temperature.

It will now be understood that the valve 26 may be moved in a manner to maintain a constant degree of superheat at the evaporator outlet, as long as the spring 59 is properly adjusted. As the cooling load on the system varies, the spring 59 will be adjusted by the motor 63 so as to vary the superheat maintained at the outlet of the evaporator and the effective cooling surface of the evaporator. By means of my unique ar.- rangement wherein the necessity of using a sealed ll with the expansion valve is eliminated, the valve may be readily applied to any refrigeration system regardless of the kind of refrigerant used therein. The use of the friction damping means eiectively prevents hunting of the system due to minute variations in superheat at the evaporator outlet, whereas accurate response of the valve due to larger variations in superheat atfor controlling the ow of refrigerant from lthe condenser to the evaporator, the combination of means for lay-passing a small amount of refrigerant from the high pressure side of the expansion valve to the evaporator outlet, said means being arranged to cause condensation of said'bypassed refrigerant, and means for controlling the position of the expansion valve in response to the rate of condensation ofthe by-passed refrigerant. f

2. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, operating means for positioning said expansion valve in a manner to maintain a substantially constant degree of superheat at the' outlet of the evaporator, said operating means including a member 'movable' in response to pressure variations on opposite sides thereof, means subjecting one side of said member to the pressure of the refrigerant on the low pressure side of the refrigerating system, means for conducting refrigerant to the opposite side of said member at a substantially constant rate, and means for conducting refrigerant from said opposite side at a rate'that depends upon the temperature of the refrigerant at the evaporator outlet whereby said other side lof said member is subjected to a pressure that varies as the pressure corresponding to the temperature of the ,refrigerant at the evaporator outlet varies 3. In a refrigerating system having a condenser, an evaporator and `an expansion valve for controlling the flow of refrigerant from the condenser 'to the evaporator, the combination of,

tion between one side of said actuating means and the low pressure side of the refrigerating system, conduit means providing communication between the high pressure side of the refrigerating system,l the other side of said actuating means andthe low pressure side .of the refrigerating system, the communication between the high pressure side of the system and said other side ofV the actuating means being of small size,-

a portionl of said conduit means being located in the evaporator outlet to cause condensation of refrigerant in said portiomwhereby the temperature of the refrigerant at theevaporator outlet determines the pressure on said other side of the actuating means.

4. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the Il ow of refrigerant from the condenser to the evaporator, the combination of, pressure responsive actuating means for said expansion valve, means providing communication between one side of said actuating means and the low pressure side of the refrigerating system, means conducting refrigerant from the high pressure side of the refrigerating system to the other side of the actuating means at a substantially constant rate, conduit means conducting refrigerantfrom said other side of the actuating means to the low pressure side ofthe refrigerating system, and a portion-of said conduit means located in the ,evaporator ,outlet to cause condensation of refrigerant in said portion, whereby the temperatureof the refrigerant at the evaporator outlet determines the pressure on said other side of the actuating means.

5. In a refrigerating system having a condenser, an 'evaporator and an expansion .valve for controlling the ow of refrigerant from the `condenser to the evaporator, the combination of, pressure responsive actuating means for said expansion valve, means providing communication between one side of said actuating means `andthe low pressure side of the refrigerating system, a small leak port between the high pressure side lof the refrigerating system and the other side of the actuating means, a tube prothe low pressure side of the refrigerating' system, means conducting refrigerant from the high pressure side 4fof the refrigerating system to the other chamberf-at a substantially constant rate, means conducting refrigerant from said other chamber to the low pressure side of the refrigerating system at a rate that varies in proportion to the variations in the pressure corresponding to the temperature of the refrigerant at the outlet ofthe evaporator, and4 a bellows within said last named chamber for decreasing the effective pressure area of the wall portion thereof and being of such a size as to insure the maintenance of a substantially constant degree pf superheat at the evaporator `outlet for varying degrees of pressure and temperature at said outlet. f

7. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, the combination of, a pair of opposed extensible chambers, one end of each of said chambers being rigidly connected together and said ends having rigid imperforate wall portions forming pressure areas, means operatively connecting the expansion valve with the connection between said chambers for. operation thereby, means connecting one chamber tothe low pressure side of the refrigerating system, means conducting refrigerant from the high pressure side of the refrigerating system to the other chamber at a substantially constant rate, means conducting refrigerant from said other chamber to the low pressure side of the refrigerating system at a rate that varies in proportion to the variations in the pressurelcorresponding to the temperature of the refrigerant at the outlet of the evaporator, a bellows within said last named chamber for decreasing the effective pressure area of the wall portion thereof and being of such a size as to insure the maintenance of a substantially constant degree of superheat at the evaporator outlet for varying degrees of presviding communication between said other side of .the actuating means and the interiorof the evaporator outlet and having a small port at the `end within the evaporator outlet, thetemperature of condensation of refrigerant leaving said tube b-eing determined by the temperature at the evaporator outlet and determining the pressure on said other side of the actuating means, said leak port being of such a size that the flow of refrigerant therethrough remains substantially constant during the operation of the re' frigerating system regardless of the temperature i of condensation within said tube, whereby the pressure 'ony said other side of the actuating means is proportional to the temperature .of the refrigerant at the evaporator outlet.`

V6. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporaton'the combination of, a pair of opposedextensible chambers, one end of each of said chambers being rigidly connected together and said ends havingrigid imperforate wall portions forming pressure areas, means operatively connecting the expansion valve with the connection between said chambers for operation thereby, means connecting one chamber to sure and temperature at saidoutlet, and means for counteracting the effects of the variations in force exerted by the extensible chambers upon expansion and contraction thereof.

8. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the ow of refrigerant from the condenser to the evaporator, the combination of, a

pair of opposed extensible chambers, one end of each of said chambers being rigidly connected together and said ends having rigid imperforate wall portions forming pressure areas, means operatively connecting the expansion valve with the connection between said chambers for operation thereby, means 'connecting one chamber to the 10W pressure side of the refrigerating system, means conducting refrigerant from the high pressure side of the refrigerating system to the other chamber at a substantially constant rate, means conducting refrigerant from said other chamber to the low pressure side of the refrigerating system at a rate that varies in proportion to the variations in the pressure corresponding to the temperature of the refrigerant at the out- .let of the evaporator, a bellows within said last named chamber for decreasing the effective pressure area of the wall portion thereof and bein of such a size as to insure the maintenance a substantially constant degree of superheat at the evaporator outlet for varying degrees of pressure and temperature at said outlet, and damping @means for preventing hunting of the expansion denser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, the combination of, meansv for by-passing a small amount of refrigerant from the high pressure side of the expansion valve to the evaporator outlet, 'means forming vpart of said lby-passing means for causing condensation of said by-passed refrigerant in the evaporator outlet, means for controlling the position of the expansion valve in response to the temperature of condensation of the by-passed refrigerant, and means for varying the force required to open the expansion valve whereby the degree of superheat maintained at the evaporator outlet 'is varied.

10. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the now of refrigerant from the condenser to the evaporator, operating means for positioning. said expansion valve in a manner to maintaina substantially constant degree of superheat at the outlet of the evaporator, said operating means including a member movable in response to pressure variations on opposite sides thereof, means subjecting one side of said member t'o the pressure of the refrigerant on the low pressure side'of the refrigerating system, means for-'conducting refrigerant to the opposite side of said member at a substantially constant rate, means for conducting refrigerant from said opposite side at a rate that depends upon the temperature of the refrigerant at the evaporator outletv whereby said other side of said member is subjected to a pressure that varies as the pressure corresponding to the temperature of the refrigerant at the evaporator outlet varies, and means for rendering the effective pressure area of said other side of the member less than the effective pressure area of said one side.

11. Ina refrigerating system having a condenser, an evaporator and-an expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, the -combination of, means responsive to the condition of the refrigerant on the low pressure side of the refrigerating system for controlling the operation of the expansionA valve, said means including resilient means-that become stressed upon operation, of the expansion valve -to various positions, and means for counteracting the'effects of the variations in force exerted by the resilient means so that stresses set up therein will not affect materially the position `of the expansion valve.

12. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporatory the 'combination of, extensible means controlling the position of the expansion valve, means causing the extensible means to respond to the superheat at the outlet of the evaporator whereby said expansion valve is` positioned in accordance with the superheat at the evaporator outlet, and means for counteracting the effects of the variations in force exerted by the extensible means so that stresses set up therein will not affect materially the position of the expansion valve.

13. In a refrigerating system having a condenser, an evaporator and an. expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, the combination of, a first bellows, a second bellows in axial alignment with said first bellows, wall means separating said bellows and movable therewith, a rod connected to said wall means and extending axially through the interior of the first bellows, spring means cooperating with the rod to urge said wall means in one direction, means for sealing the interior of the second bellows and for subjecting the interior thereof to the pressure of the low pressure side of the refrigerating system, a sealing bellows connected to the rod for sealing the interior of the first bellows, means for subjecting the interior of the first bellows to a pressure corresponding to the temperature of the refrigerant inthe outlet, of the vaporator, means operated by the Wall means for` operating the expansion valve, and means cooperating with said rod for substantially counteracting the effects of the variations in force exerted by the spring means and the bellows upon expansion and contraction thereof.

14. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the iiow of refrigerant from the condenser to the evaporator, the combination of, a pair o-f opposed extensible chambers, one end of each of said chambers being rigidly connected together and said ends having rigid imperforate wall portions forming pressure areas, means operatively connecting the expansion valve with the connection between said chambers for operation thereby, means subjecting one chamber to the low pressure sideof the refrigerating system, means subjecting the other chamber to a pressure which corresponds to the temperature of the refrigerant at the evaporator outlet, a bellows within said last named chamber for decreasing the effective pressure area of the wall portion thereof and being of such size as to insure the maintenance of a substantially constant degree of superheat at the evaporator outlet for varying degrees of pressure and temperature at said outlet, and means for substantially counteracting the effects of the variations in force exerted by the extensible chambers upon expansion and contraction thereof.

15. In a refrigerating system having a condenser, an evaporator and an expansion valve for controlling the flow of refrigerant from the condenser to the evaporator, the combination of, means including an expansible chamber for positioning the expansion valve, means for supplying a restricted amountl of refrigerant from the y high pressure side of the refrigerating system to the expansible chamber, means for withdrawing refrigerant from the expansible chamber, means responsive to the condition of the refrigerant at the outlet of the evaporator for regulating the lerating means including an expansible chamber for positioning the expansion valve, means for suppling a restricted amount of refrigerant from the high pressure side of the refrigerating system to the expansible chamber, means for withdrawing refrigerant from the expansible chamber and means responsive to the temperature of the re- 2,298,804 p frigerant atzthe outlet of the evaporator for reg- Y tively warmregionsoas to evaporate the refrigerant `therein,imeans for communicating refrigerant from said chamber toa pointspaced i therefromfrestricted means for Icausing refrigerant to escape from `said communicating means,

f said last restricted means `beingof a size to allow `tends to constantly escape of gas at a slower rate than that atwhich refrigerant enters said chamber, means whereby said `communicating means is subjected to the cooling `effect of the relatively cool refrigerant at the'outlet ofthe evaporator so as to cause refrigerant to condense in said communicating means andescape as a liquid from said last 'i'estricted means whereby a small amount of liquid and communicating means corresponds to the condensation temperature of said liquid. v

` lALWIN B. NEWTON.

stand in said communicat- A ling means so that the pressure inrsaid chamber 

